HSI overhaul

Been seeing some intermittent issues with the non-slaved NSD360 as of late. I contacted Castleberry and spoke with a tech who really sounded like he knew the unit inside and out. Got a quote for overhaul just under $2k. Anyone with experience with Castleberry?

I also have a NSD36A that’s having issues. I’m seriously considering the G5 to replace it. It’ll be a little over double the price, but I have a goal of getting rid of the vacuum system eventually. This would be step 1.

I had a Castleberry AI that failed, sent it to them for repair/overhaul. Don't remember the cost, but it seemed reasonable. Turnaround was prompt, had a warranty issue, immediately and courteously handled, and it has worked perfectly for five or six years since.

I’d look at other options over the G5, some other glass out there, the G5 is a VERY basic HSI, it doesn’t have any overlays or weather or range rings or anything like that, frankly for all the things they can do with glass technology it’s majorly lacking.

I had just a plain vacuum,non-slaved DG with heading bug whose output to the autopilot had failed and I was given an estimate of $1500 to overhaul it. Vacuum pump was also on the verge of needing to be replaced so I went with a G5 HSI and GMU 11 magnetometer to complement the G5 attitude unit I had previously installed. Gained about 9 pounds in useful load because the vacuum system was totally removed. Net $ outlay, of course, but not by a lot.

I’d look at other options over the G5, some other glass out there, the G5 is a VERY basic HSI, it doesn’t have any overlays or weather or range rings or anything like that, frankly for all the things they can do with glass technology it’s majorly lacking.

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It's a software issue. Give Garmin time, the software will be updated to do more. Same for the L3 - when I talked to the L3 guys in '15, I commented about additional features I'd like to see. wink wink, nod nod, it's a software issue - working on it for the future.

If you have an older king gps you are pretty much stuck overhauling the gyro. Most of the Digital HSI units want talk with the gps.

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Okay, which King unit?

I had a KLN-94 until a couple of years back. Liked that GPS. Upgraded to a GTN650.

If you have to overhaul this thing another couple of times at $2k/pop (does that even include removal and re-installation?) you start to eat pretty heavily into the cost of an upgrade GPS.

That money spent keeping a mechanical HSI running is throwing money away. You're going to upgrade that GPS eventually... why not spend that overhaul money on that, instead? At least, that would be my thinking.

I had a KLN-94 until a couple of years back. Liked that GPS. Upgraded to a GTN650.

If you have to overhaul this thing another couple of times at $2k/pop (does that even include removal and re-installation?) you start to eat pretty heavily into the cost of an upgrade GPS.

That money spent keeping a mechanical HSI running is throwing money away. You're going to upgrade that GPS eventually... why not spend that overhaul money on that, instead? At least, that would be my thinking.

I’m in the same boat. The gyro in my King HSI needs overhauled. $2300 for a refurbished unit. The shop quoted me a G5 HSI replacement at $6-7K depending on issues encountered during installation. That including removing the King HSI. I opted to go with the replacement gyro. The G5’s are nice and I can install either one without affecting my autopilot but that is still a lot for no meaningful difference in functionality.

I get the autopilot interface issues. It's a big-time consideration, obviously.

I also understand the "spend $2k and keep trucking for now" vs. $5-7k for terminating the upgrade costs. Sometimes the short term solution makes more sense in the grand scheme.

I would just feel sick spending the money keeping a mechanical HSI running when those things have already reached economic obsolescence. Those are going to be novelty items within ten years.

I'm one to talk, though. My airplane needs a paint job. I found a really good painter. I tried to talk him into a touch-up paint job. "This plane needs a new paint job. Touch up work is a waste of money," he told me.

Yet I convinced him to just cover the bare metal for about $1500, for now. "This is only going to buy you a couple of years," he warned me.

I get the autopilot interface issues. It's a big-time consideration, obviously.

I also understand the "spend $2k and keep trucking for now" vs. $5-7k for terminating the upgrade costs. Sometimes the short term solution makes more sense in the grand scheme.

I would just feel sick spending the money keeping a mechanical HSI running when those things have already reached economic obsolescence. Those are going to be novelty items within ten years.

I'm one to talk, though. My airplane needs a paint job. I found a really good painter. I tried to talk him into a touch-up paint job. "This plane needs a new paint job. Touch up work is a waste of money," he told me.

Yet I convinced him to just cover the bare metal for about $1500, for now. "This is only going to buy you a couple of years," he warned me.

I'm just not ready to drop $20k on paint right now.

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Just curious, what makes the G5 any different than an HSI? I realize some people have had back to back to back gyro failures but for the most part they go years with trouble free service. For people with older panels a G5 just doesn't make sense not to mention they haven't been in service long enough to know if they will be any more durable than a gyro.

Just curious, what makes the G5 any different than an HSI? I realize some people have had back to back to back gyro failures but for the most part they go years with trouble free service. For people with older panels a G5 just doesn't make sense not to mention they haven't been in service long enough to know if they will be any more durable than a gyro.

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Flags will never stick, needles will never stick, syncro belt will never break, bearings will never be rough, weighs much less, takes up less space, can run on it's own rechargeable battery for about 5 hours. Replacement batteries are under $200.

Just curious, what makes the G5 any different than an HSI? I realize some people have had back to back to back gyro failures but for the most part they go years with trouble free service. For people with older panels a G5 just doesn't make sense not to mention they haven't been in service long enough to know if they will be any more durable than a gyro.

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What makes it any different?

It's an EHSI. More reliable. More capable. Doesn't break. No moving parts. Doesn't require overhaul. Offers reversionary mode to a G5 ADI. Software upgrades are already improving its featureset (more to come, free.) Has a backup battery. Is the same price or less than a mechanical HSI. No ongoing maintenance. Need I go on? There's a reason the market is getting flooded with these things. Just about everyone in the budget upgrade category is moving to the G5 pair.

It's a no-brainer replacement for a mechanical HSI which needs an overhaul, if it interfaces with existing equipment and autopilot. In most cases it will, but in some, it won't. That's when it becomes more of a judgement call.

Don't think I have ever had any of that happen on my HSI either. Takes up the same amount of panel space. The weight savings would be nice but it's a pretty small drop in the bucket. You could be trading all of those mechanical failures for screen failures in 5 years so nothing is a guarantee.

It's an EHSI. More reliable. More capable. Doesn't break. No moving parts. Doesn't require overhaul. Offers reversionary mode to a G5 ADI. Software upgrades are already improving its featureset (more to come, free.) Has a backup battery. Is the same price or less than a mechanical HSI. No ongoing maintenance. Need I go on? There's a reason the market is getting flooded with these things. Just about everyone in the budget upgrade category is moving to the G5 pair.

It's a no-brainer replacement for a mechanical HSI which needs an overhaul, if it interfaces with existing equipment and autopilot. In most cases it will, but in some, it won't. That's when it becomes more of a judgement call.

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I get that it makes sense if you are faced with a 2.5k gyro overhaul but only if you can utilize it's other features. Otherwise you just spent more money to have something that does the same thing with an unknown dispatch rate.

Don't think I have ever had any of that happen on my HSI either. Takes up the same amount of panel space. The weight savings would be nice but it's a pretty small drop in the bucket. You could be trading all of those mechanical failures for screen failures in 5 years so nothing is a guarantee.

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No way. I've flown behind countless mechanical HSIs. Glad you had a good run with yours, but they all break... they ALL break. Usually at the worst possible time. Like bnt83 mentioned, you get sticking flags, sticking indicators, precession issues, the works. It's not surprising... if you ever have a chance to look inside one of these things while they're being taken apart, take note of how many little delicate parts are contained within. You practically need watchmaker skills to work on them. They're sensitive and prone to failure, and that's why they cost so much to maintain. That's also why I never installed one in my airplane. It took the current wave of inexpensive EHSIs to make it all come together. Heck, they don't cost more, in most cases they cost less, and they're better... and safer. It's an easy call.

They take less space behind the panel. They're tiny. They weigh almost nothing.

I would estimate the chance for a screen failure to be an order of magnitude less than the chance of some kind of parts problem with a mechanical HSI. Of course the odds aren't zero, but they're extremely slim... vs. a nearly 100% chance that a mechanical HSI will need work every few years.

The only logical reason to stick with a mechanical HSI is a) it's running fine right now anyway (fine, keep it until it breaks, then) or b) a G5 HSI won't interface with your current stack. That becomes problematic on a couple of levels so do what you've gotta do.

Otherwise, it truly is a no-brainer. Replace and ugprade for the cost of yet another overhaul.

if you ever have a chance to look inside one of these things while they're being taken apart, take note of how many little delicate parts are contained within. You practically need watchmaker skills to work on them.

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One of the shops that does the actual gyro overhauls is somewhere in LA. The crew is mostly middle aged vietnamese ladies. It's a job that requires the ability to work with loupes and tweezers for 8hrs a day and there are few who have the fine motor skills and patience to do this.

The only logical reason to stick with a mechanical HSI is a) it's running fine right now anyway (fine, keep it until it breaks, then) or b) a G5 HSI won't interface with your current stack. That becomes problematic on a couple of levels so do what you've gotta do.

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That's what we are doing now but I'll propose to my partners to pre-plan that the next time the thing tries to eat another $2500 we'll just pull the trigger on the replacement.

No dog in the fight, and I'm not disputing mechanical brass breaks, but ill continue to push back on this myth that glass legacy mx costs are zero. Ask aspen owners how that's working for them. Uncle won't be giving ya warranty claims ad infinitum.

No dog in the fight, and I'm not disputing mechanical brass breaks, but ill continue to push back on this myth that glass legacy mx costs are zero. Ask aspen owners how that's working for them. Uncle won't be giving ya warranty claims ad infinitum.

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The mechanical gyros in my 1979 plane are older than every single computing device I have in active service today.
Every . single . computing . device.
Phone, computer, tablet, watch, cars, the 8 year old oven in the kitchen with the twice failed digital control panel, the solid state controlled boilers in my home and detached garage, one of which has also failed twice in 8 years...
Wanna bet the G5s are throwaways instead of repairable?

I’m in the same boat. The gyro in my King HSI needs overhauled. $2300 for a refurbished unit. The shop quoted me a G5 HSI replacement at $6-7K depending on issues encountered during installation. That including removing the King HSI. I opted to go with the replacement gyro. The G5’s are nice and I can install either one without affecting my autopilot but that is still a lot for no meaningful difference in functionality.

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That’s a lot of $$ for just the HSI, mine was 8k including the AI and GAD 29B for AP and moving the Vacuum driven AI to TC hole and pitot static inspection.

Following up, I remembered that I had this unit overhauled several years ago. Log shows Mid-Continent (not Castleberry), and the year was 2000 or about 1,000 hours ago. Not too bad on the service of the unit, for those who expressed doubt on mechanical overhauls. Will give them a call to see what their estimate would be for repair, since the budget calls for ADS-B compliance for next year.... the saga continues.